Hi all, I am attempting to model large scale atmospheric movement in CFX 4.4. I am at present having it rough with the specifications of pressure boundary conditions(maybe) and specifications of buoyancy forces(maybe)... My flow domain needs to be large, therefore the flow field can be considered compressible. Has anyone had any experience in atmospheric modeling with CFX or any other CFD package and could contact me or anyone else who might have aby questions and/or ideas? Any help will be appreciated. Cheers

People at CFX UK have done such work with CFX-4. I believe publications appeared in J. Wind Eng. and Ind. Aero in 1998 (?) and also in CFX Update. Speak to the za agent so that he can pass on the details to you.

More specific, it is Swiss lady, currently working at the helpdesk in Harwell (UK) who has done this before. So ask the helpdesk....

Astrid

Rhydar Her name is Christian Montavon (hope thats spelt correctly!) She has modelled Atmospheric boundary layers using CFX4 and looked at pollutant dispersion I think as well as mountain waves (just going by memory of papers I've seen). You can also use CFX5 to model atposheric Boundary layers, but as yet I don't think I've seen any papers using this version of the code. What specifically were your problems ?? Did you have problems with the down steam boundary ? Does the model have to be compressible ? Bob

ChristianE (she's a lady!)

Hi Bob I have managed to track down the paper, thanks. I am attempting to model the flow field above a "Solar Chimney" power plant. My flow domain has to be larger than the height of the chimney, 1500m, I have chosen 5000m as my height, over this height for adiabatic conditions the pressure change is about 45kpa, therefore the decision to use compressible option. My problem arises with the specification of pressure boundaries on the top and side, 2D axisymmetric flow. I am attempting to get a "stable" atmosphere at the moment, i.e stratified pressure and temperature with zero flow field. But to no luck, my flow field is unstable and ridiculously high velocities result. Any ideas will be greatly appreciated!?! Thanks again. Rhydar

I believe C montavon included the solution of the potential temperature in the solution to look at stable atmospheric conditions.

Salut Holidays! J'espere on peut faire un rendev-vous a Guilers/Bohars a Noel.

Indeed she did an extra coupling other than the density gradient.

Bob, I'll be in Brazil later this year; another time maybe when you visit... Best wishes to Isa and you.

Hi,

I have do some simulation on a small island for Hong Kong. And the difficulty is to simulate the complex terrain. I have 4000 topographic datapoint. As I am using the standard wind code. I do not got the problem you mentioned. But can you tell me how fine resolution you want to do?

Jim

Sorry Holidays, Not too hot on all the spelling Bob